D-Rev designs medical devices for the 4 billion people who live on less than US$ 4 a day. This means understanding the needs of users and fundamentally rethinking devices that were designed for more affluent markets.

For example, high-quality prosthetic knees are typically made from titanium and cost thousands of dollars. Most of the world’s amputees instead have to rely on cheaper and cruder devices that typically do not cope well with kneeling, squatting or keeping balance on uneven terrain.

D-Rev’s ReMotion knee, made from injection-moulded plastic, offers vastly better performance at less than one-tenth the cost of high-end devices. Around 5,000 knees have been fitted, and the latest version of the knee is set to enter mass production in the coming months.

D-Rev is also scaling Brilliance, a blue-light phototherapy unit for treating severe jaundice – the top reason why new-borns are readmitted to hospitals worldwide, and which can be fatal if untreated. By using LED instead of fluorescent lights, Brilliance nearly eliminates operating and maintenance costs. It is also designed to manage voltage surges characteristic of developing countries, and variable treatment surfaces common in busy hospitals.

Although D-Rev sells its devices for profit, it is incorporated as a non-profit and uses grants for research and development; several new products are in the pipeline. Non-profit status allows D-Rev to make an impact on its bottom line: each Brilliance device, for example, counts how many babies have been treated, data that can feed into improving the design. Selling instead of donating guarantees that people genuinely value – and ideally use – D-Rev’s products.